Speed responsive control for electric switch



Aug. 14, 1956 L. E. THATCHER SPEED RESPONSIVE CONTROL FOR ELECTRIC SWITCH Filed April 7, 1955 F511. N F513.

Y i Q i 44 7 ||||n1|w\ 2 1 2 V j 19 K 20 18 My 1 i W" 20 ////V (37 ///7 w y y SPEED RESPGNSWE CQNTROL FOR ELECTRIC SWITCH Lewis E. Thatcher, Chicago, 111., assignor to Gaylord Products Inc, Chicago, Ill, a corporation of Delaware Application April 7, 1955, Serial No. 499,991

7 Claims. (Cl. 20080) This invention relates to improvements in an electric switch which is responsive to the rotary movement or rotary speed of a rotating body.

In many environments, particularly in conjunction with automotive vehicles, it is desirable to control an electric circuit in response to the rotary speed of a rotating body. For instance, in speed governors for automotive vehicles or in so-called anticreep devices for automobiles it is desirable to exercise a control in response to the speed of movement of the vehicle. The most convenient way to exercise such control is to transform the translatory speed of the vehicle into rotation of a rotating body shaft or cable and by means of such rotation actuate an electric switch which may energize or deenergize an appropriate electric circuit to exercise the desired control.

The present invention relates particularly to a device which in response to the speed of rotation of a rotating body may energize or deenergize an electrical control circuit.

One of the important features of the present invention resides in a relatively simple structure for actuating such control, the device being reliable in operation, having a minimum of moving parts and being economical to manufacture.

Another important feature of the invention resides in the simplicity in which the device may be calibrated to operate at a predetermined speed.

Briefly described, the device comprises a pair of spaced discs which are positively driven by a rotating body. Interposed between the two spaced discs is a third disc which loosely embraces the rotating body. A springactuated switch arm bears upon the peripheral edge of the third disc to normally urge said disc to an eccentric position with respect to said spaced discs and the rotating body. Forceproducing means frictionally engages the spaced discs with the third disc to tend to rotate said third disc with the rotating body and the spaced disc whereby said third disc exerts a radical force on said spring-actuated arm tending to actuate the switch as the body rotates.

Other objects and advantages of the present invention will be apparent from the accompanying drawing and following detailed description.

In the drawing,

Fig. 1 is a longitudinal sectional view through a housing, taken on line 1-1 of Fig. 2 illustrating the control assembly.

Fig. 2 is a plan sectional View taken on line 22 of Fig. 1.

Fig. 3 is a view similar to Fig. 1 illustrating a modification of the invention.

Fig. 4 is a plan sectional view taken on line 4-4 of Fig. 3.

For puiposes of illustrating the operation of the device, it will be described in its use upon an automotive vehicle and for convenience the speedometer cable of the automobile will be used as the rotating body from .nited States Patent 2,759,059 Patented Aug. 14, 1956 which the control is exercised. Of course, the device may be used in environments other than on an automobile and if used on an automobile, other rotating portions of the automobile may be employed as the rotating body from which the control is exercised.

Referring in detail to the drawing, 1 indicates a cupshaped housing which is open at one end, the housing having a closed bottom 2'. A cylindrical extension 3 is formed integral with the bottom 2 and extends outwardly centrally from the bottom. The extension 3 is provided with a longitudinal bore 4 in which a rotatable shaft 5 is adapted to be journaled. The shaft 5 may comprise a portion of the device itself or may, if desired, be a portion of the speedometer cable of an automobile. If the shaft 5 comprises a portion of the device itself suitable coupling means will be made at the ends of the device (not shown) whereby the shaft 5 may be coupled to the speedometer cable. The outer periphery of the extension 3 may carry threads 6 whereby it may be secured to a suitable coupling which, for instance, may be carried by the speedometer cable sheath (not shown).

A disc cover 7 may be positioned at the open end portion of the housing 1, said disc also having an extension 8 provided with a central bore 9 for the reception of the rotatable member 5. The extension 3 may also be provided with threads id whereby said extension rnay also be coupled to the speedometer cable sheath (not shown). The disc cover '7 may be secured to the upper edge of the housing 1 by means of a suitable cement or the like ll.

A boss i2 is formed integral with the bottom 2 and extends inwardly into the housing 1 and a similar boss 13 is formed integral with the cover i and also extends inwardly with respect to the housing ll. Within the housing a disc 14 may be carried by shaft 5, said disc being supported upon boss 12 and being keyed by means of key 15 to shaft 5. A similar disc 16 is carried upon shaft and bears against boss 13, the disc 16 being keyed to shaft 5 by means of key 17. The arrangement is such that when shaft 5 rotates both discs 14 and i6 rotate therewith.

A central disc 13 is positioned between the discs 14 and 16, the central disc being provided with a relatively enlarged central opening 19 whereby said disc loosely embraces shaft 5. The opening i9 is materially larger in diameter than the diameter of shaft 5 whereby the disc 18 may move radially with respect to said shaft to an eccentric position with regard to the discs 1 and 16. Disc 14 carries a plurality of permanent magnets which are circumferentially spaced from each other. In the form of the invention illustrated four such permanent magnets are shown, being spaced 99 from each other. One end of each of the 219 is flush with the surface of disc i i whereas the opposite end of each of the magnets extends outwardly from the opposite surface of the disc toward the central disc 13. The disc to also carries a plurality of permanent magn ts 21 rich are positioned in the disc 16 in a fashion similar to the posi tioning of the magnets Ztl in the disc 14. in this fashion the central disc 18 is confined between the magnets 20 carried by the disc 14 and the magnets 21 carried by the disc 16.

The keys 15 and 17 permit a slight degree of axial movement of the discs 14 and 16 upon the shaft 5 and the discs 14, 16 and 18 are constructed of a ferro-magnetic material and thus the discs 1 18 and 16 comprise essentially a unit structure, the disc 18 being held as part of the unit by the magnetic pull of the magnets 29 and 21.

The lateral walls of the housing 1 provide a lateral compartment 22 at one side of the housing. Within the compartment 22 a conventional snap switch 23 is positioned. The switch 23 comprises an L-shaped frame 24 secured to the wall of the housing by rivets or the like 25. A fulcrum support 26 is carried by the frame member 24 and an arm 27 is pivotally secured to the support 26, said arm being bent at right angles at one end as at 28 in Fig. 2 and the end portion of said arm being adapted to bear against the periphery of disc 18. The frame member 24 carries an electrical contact 29 to which an electrical conductor 30 is connected. The frame member 24 also carries an insulated contact 31 to which an electrical conductor 32 is connected, the contact 31 being insulated from the body of the frame member 24. A switch arm 33 is pivotally secured to the support 26 and engages with an end of the arm 27. A spring member 34 bears upon the switch arm 33, the arrangement being such that a spring impelled toggle switch results. The switch 23 per se is conventional and does not comprise a portion of the present invention. The switch 23 comprises a portion of an external electric circuit (not shown) being connected thereto by means of conductors 3t) and 32.

In operation, the arm 27 is normally impelled by spring 34 so that the bent end thereof exerts a radial inward force upon the central disc 18. When the shaft is stationary the disc 18 will be in the position shown in Figs. 1 and 2 and switch 23 will be closed. As the the shaft 5 rotates the discs 14 and 16 rotate in step therewith. By virtue of the attractive force of the magnets and 21 upon the disc 18, the disc 18 tends to rotate. However, the spring impelled arm 27 tends to hold the disc 18 in the eccentric position illustrated in Figs. 1 and 2. Thus, the central disc 18 is subjected to two opposing forces, the force of friction of the magnets upon the disc 18 and the resilient radially inwardly directed force exerted by the arm 27 upon the disc 18. As rotation of the shaft 5 increases the force of friction exerted by the magnets upon the disc 18 increases until a rotational speed is reached at which said force exceeds the force exerted upon the disc 18 by the arm 27. When the frictional force begins to exceed the resilient force of the arm 27 the disc 18 tends to move into a concentric position with respect to the shaft 5 and discs 14 and 16. In so moving, the switch arm 33 eventually snaps away from the contact 31 and thus opens the circuit to which the conductors and 32 are connected.

It can readily be seen that inasmuch as the functioning of the device depends upon three factors, that is, the frictional force exerted by the magnets, the resilient impelling force exerted by the arm 27 and the rotational speed of the shaft 5, the period at which the switch 23 may be opened can be changed by changing the strength of the magnets 20 and 21 or their number and/or by changing the resilience of the switch 23 by using a stronger or weaker spring 34. In this fashion the switch 23 can be opened in response to substantially any predetermined speed of rotation of the shaft 5.

A pair of stop pins 35 and 36 may be positioned within the housing 1 adjacent the periphery of the discs 14 and 16, the pins 35 and 36 being disposed on opposite sides of the bent portion 28 of the arm 27. The pins 35 and 36 function as stops for the disc 18 when it moves to its concentric position with respect to the discs 14 and 16.

Referring particularly to Figs. 3 and 4 a modification of the invention is shown. In the modified form of invention, 37 indicates a cup-shaped housing having an open top and a bottom 38. An extension 39 is carried by the bottom 38, said extension being provided with threads 40. A disc cover 41 is adapted to be positioned upon the upper edge of the lateral wall of the housing 37 and is secured thereto by means of cement 42. An extension 43 is formed integral with the disc 41, said extension being provided with external threads 44. The

extensions 39 and 43 are provided with central bores 45 and 46 respectively for the reception of a rotatable shaft 47. The shaft 47 corresponds to the shaft 5 hereinbefore described and may comprise the speedometer cable itself or may comprise a portion of the control device whereby the ends of the speedometer cable would be coupled to the ends of the shaft 47. Disc 43 is positioned within the housing 37 and is keyed by means of key 49 to shaft 47. A second disc 56 is slidably and rotatably positioned upon the shaft 47 and between the discs 48 and 50 a central disc 51 is positioned. The central disc 51 is provided with a central aperture 52 which is of a diameter in excess of the diameter of the shaft 47 whereby disc 51 may move radially with respect to the discs 48 and 50 and the shaft 47.

A collar 53 is mounted upon shaft 47 within the housing 37, said collar being keyed by means of key to the shaft 47. A coil spring 55 embraces a portion of shaft 47 between collar 53 and disc 50, one end of said coil spring being anchored in disc 53, as at 56 in Fig. 3, and the opposite end of said coil spring being anchored in disc 50, as at 57 in Fig. 3.

The arrangement is such that when shaft 47 rotates, collar 53 and disc 48 rotate in step therewith. However, disc 50 is not directly secured to shaft 47 but it will be rotated through the agency of the coil spring 55. The coil spring 55 in addition to functioning as a resilient driving member for disc 50, also urges said disc into frictional contact with the central disc 51. Thus, by means of spring 55 the central disc 51 frictionally engages both the discs 50 and 48.

The housing 37 is provided with a lateral extending compartment 58 in which a conventional snap switch 59 is positioned. The switch 59 is identical with switch 23 hereinbefore described and carries an arm 69 which bears against the peripheral edge of the central disc 51. The switch 59 comprises a portion of an external control circuit (not shown) to which it is connected by means of conductors 61 and 62.

In the operation of the form of the invention shown in Figs. 3 and 4 the arm normally tends to move the central disc 51 to an eccentric position with respect to the discs 48 and 50, that is, the position illustrated in Figs. 3 and 4. However, when the shaft 47 rotates the frictional force exerted upon the disc 51 by the discs 48 and 50 tends to create a force which opposes the resilient force of arm 60. As the speed of the shaft 47 increases the frictional force thus exerted increases and eventually the force of friction of the disc 51 with respect to the discs 48 and 50 overcomes the resilient force of the arm 69 and the switch 59 is opened.

In view of the fact that the frictional force of disc 51 with respect to discs 48 and 50 is dependent upon the compressive strength of spring 55, this force may be increased or decreased by changing spring 55 to a heavier or lighter spring. As has been hereinbefore described, the spring as sociated with switch 59 may also be changed to vary the balancing of the forces involved. In addition, the period at which switch 59 may be opened may be changed by changing the coefficient of friction of the contacting surfaces of discs 51, 48 and 50 by substituting discs of materials having greater or lesser coefiicients of friction or by lining the inner faces of the discs 48 and 51B and the outer faces of the disc 51 with material having greater or lesser coefiicients of friction.

In both forms of the invention, the devices may be employed to control a speed governing circuit or an anticreep circuit upon an automobile. However, it can readily be seen that the rotating shafts 5 and 47 may be connected in other environments to effect other controls by electric circuits suitably connected to switches 23 or 5'9.

I claim as my invention:

1. A speed responsive control for an electric switch which comprises a pair of spaced members adapted to be mounted upon and rotate with a rotating body, a central member positioned between said spaced members,

said central member being adapted to loosely embrace said rotating body nd being laterally and circumferentially movable with respect to said body and said spaced members, a resiliently impelled arm disposed adjacent said members and in contact with said central member to urge resiliently said central member radially to an cccentric position with respect to said spaced members and said rotating body, means for urging said spaced members and central member into frictional engagement with each other whereby rotation of said spaced members tends to rotate said central member which exerts a force upon said arm in opposition to said resilient impelling force to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

2. A speed responsive control for an electric switch which comprises a pair of spaced discs adapted to be mounted upon and rotate with a rotating body, a central disc positioned between said spaced discs, said central disc being adapted to loosely embrace said rotating body and being laterally and circumferentially movable with respect to said body and said spaced discs, a resiliently impelled arm disposed adjacent said discs and in contact with the peripheral edge of said central disc to urge resiliently said central disc radially to an eccentric position with respect to said spaced discs and said rotating body, means for urging said spaced disc and central disc into frictional engagement with each other whereby rotation of said spaced discs tends to rotate said central disc which exerts a force upon said arm in opposition to said resilient impelling force to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

3. A speed responsive control for an electric switch which comprises a rotatable shaft, a pair of spaced members mounted upon and rotatable with said shaft in planes at right-angles to said shaft, a central member positioned between said spaced members, said central member loosely embracing said rotatable shaft and being radially and circumferentially movable with respect to said shaft and said spaced members, a resiliently impelled arm disposed adjacent said members and in contact with the peripheral edge of said central member to urge resiliently said central member radially to an eccentric position with respect to said spaced members and said rotatable shaft, means for urging said spaced members and central member into frictional engagement with each other whereby rotation of said spaced members tends to rotate said central member which exerts a force upon said arm in opposition to said resiliently impelling force to move sa d arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

4. A speed responsive control for an electric switch which comprises a rotatable shaft, a pair of discs mounted in spaced relationship upon said shaft and rotatable ther with in planes substantially at right angles to said shaft, a central disc positioned between and in plane-parallel relationship to said spaced discs, said central disc loosely embracing said rotatable shaft and being radially and circumferentially movable with respect to said shaft and said spaced discs, a resiliently impelled arm disposed a-djacent said discs and in contact with the peripheral edge of said central disc to urge resiliently said central disc radially to an eccentric position with respect to said spaced discs and said shaft, means for urging said spaced discs and central disc toward each other to frictionally engage the discs whereby rotation of said spaced discs tends to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

5. A speed responsive control for an electric switch which comprises a rotatable shaft, a pair of discs mounted in face-to-face spaced relationship upon and rotatable rotate said central disc which exerts a force upon said arm in opposition to said resiliently impelling force to with said shaft, a central disc positioned between and in face-to-face relationship with respect to said spaced discs, said central disc loosely embracing said shaft and being radially, axially and circumferentially movable with respect to said shaft and said spaced discs, a resiliently impelled arm disposed adjacent the periphery of said discs and in contact with the peripheral edge of said central disc to urge resiliently said central disc radially to an eccentric position with respect to said spaced discs and said shaft, means for urging said spaced discs and central disc into face-to-face frictional engagement with each other whereby rotation of said spaced discs tends to rotate said central disc which exerts a force upon said arm in opposition to said resiliently impelling force to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

6. A speed responsive control for an electric switch which comprises a rotatable shaft, a pair of discs mounted in face-to-face spaced relationship upon and rotatable with said shaft, a central disc positioned between and in face-to-face relationship with respect to said spaced discs, said central disc loosely embracing said shaft and being radially, axially and circumferentially movable with respect to said shaft and said spaced discs, a resiliently impelled arm disposed adjacent the periphery of said discs and in contact with the peripheral edge of said central disc to urge resiliently said central disc radially to an eccentric position with respect to said spaced discs and said shaft, resilient means for urging said spaced discs and central disc axially together in face-to-face frictional engagement with each other whereby rotation of said spaced discs tends to rotate said central disc which exerts a force upon said arm in opposition to said resiliently impelling force to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

7. A speed responsive control for an electric switch which comprises a rotatable shaft, a pair of members mounted in spaced relationship upon and rotatable with said shaft, a ferro-magnetic central member positioned between said spaced members, said central member loosely embracing said shaft and being radially, axially and circumferentially movable with respect to said shaft and said spaced members, a resiliently impelled arm disposed adjacent said members and in contact with said central member to urge resiliently said central member radially to an cecentric position with respect to said spaced members and said shaft, said spaced members comprising magnetic means for urging all of said members together into frictional engagement with each other whereby rotation of said spaced members tends to rotate said central member which exerts a force upon said arm in opposition to said resiliently impelling force to move said arm, and an electric switch connected to said arm which is actuated by predetermined movement of said arm.

References Cited in the file of this patent UNITED STATES PATENTS 1,980,107 Stern Nov. 6, 1934 2,552,036 Duzy May 8, 1951 2,589,496 Hovel Mar. 18, 1952 

